Van den Berg, V., Salimi, R., de Groot, R. H., Jolles, J., Chinapaw, M. J., & Singh, A. S. (2017). “It’s a Battle… You Want to Do It, but How Will You Get It Done?”: Teachers’ and Principals’ Perceptions of Implementing Additional Physical activity in School for Academic Performance. International Journal of environmental research and public health, 14(10), 1160.